I think a lot of the necessary legislation is already there. The difficulty is working out who might be responsible for the artefacts listed.
I'm only speculating here, but the example of PYO might be an interesting one; The land may be owned by a large estate that sub-let (maybe a hundred years ago or more) to a company (and/or successive companies) that bought a lease to exploit the mineral rights. If the company that had the last working liability for the site has gone bust/disappeared and has no assets, who do you pursue to maintain the artefacts it should have had liability for ?
Then there's whole issue of how you should conserve/preserve/restore these particular assets. Dealing with the buildings and their contents ought to be straight forward, but the existent standing Blondin is quite a complex issue, not to say potentially extremely expensive.
It's worth reading 'Welsh Highland Railway Renaissance' by Gordon Ruston about the complications of dealing with old industrial assets and how difficult it is to deal with collapsed companies and their liabilities.